The liver is the largest organ having a variety of functions over 500 functions, and works not only to reprocess various nutrients having been absorbed by intestines to supply the resultants to the other organs and store an excessive portion but also to make a large number of actions necessary for sustaining life, such as generation and secretion of bile, detoxification and excretion. This organ is, however, easily disturbed by various factors such as irregular life, stress, viruses, drugs, alcohols, undernourishment and hepatic circulatory system disorder, which may lead to a disease such as acute hepatitis, chronic hepatitis, fatty liver or liver cirrhosis in some cases. In Japan in particular, it is said that 15% or more of adults (estimated as 1.5 to 2 million persons) have fatty liver, and the spread to the young generation has become a serious social problem.
It was regarded that fatty liver is a pathological condition relating mainly to alcoholic liver disease caused by drinking an excessive amount of alcohol. Alcoholic fatty liver refers to a pathological condition in which fat is accumulated in the liver of alcohol drinkers to form fat droplets in liver cells, and fat (neutral fat in particular) is further deposited in the liver cell to cause the liver damage. In recent years, however, it has been found that findings similar to alcoholic liver disease occur even in non-drinkers.
An example of the pathological condition of fatty liver disease occurring in non-drinkers includes non-alcoholic fatty liver disease (NAFLD). NAFLD is such simple fatty liver that about 90% of patients of the disease can improve the symptom by proper diet therapy or exercise therapy although fatty liver including deposition of neutral fat in liver cells is found.
It is known, however, that about 10% of cases of NAFLD is non-alcohol steatohepatitis (NASH) corresponding to a progressive pathological condition. Although medical consensus on histopathological progression of NASH has not been obtained yet, it is regarded that a certain consensus has been built that liver cells having fat accumulated therein are modified or necrosed to cause steatohepatitis having inflammatory findings or fibrogenesis in liver tissue. Besides, it is said that a probability that fatty liver progresses to NASH, and further to more serious liver fibrosis, liver cirrhosis or liver cancer is higher in a subject suffering from multiple risk factors such as metabolic syndrome, obesity, diabetes, hyperlipidemia, hypertension and hyperuricemia.
On the other hand, ume (the flesh of ume) has been known from old days as home remedy for fatigue recovery, food poisoning and the like, and a food for inducing autophagy containing a neutralized product of ume extract (ume flesh extract) (see, for example, patent document 1), a liver function improving agent for a patient of viral hepatitis containing a neutralized product of ume extract (see, for example, patent document 2) and the like have been proposed. Besides, it has been reported that ume extract obtained by concentrating, 20 times by heating, an ume squeezed liquid prepared by squeezing ume, neutralizing the resultant with NaOH, and sterilizing the resultant by heating is effective for galactosamine hydrochloride-induced acute liver injury rat (for example, see non-patent document 1).